It is not possible to edit documents. Same issue when trying again using the admin account which has full permissions.
The button "Edit" is grayed out (dimmed) and the document is not editable:


Please check if there is version managament activated for this file cabinet.
Initially, when version management is activated, you are able to select Edit from the context menu. DocuWare automatically increments the version number for the document after it is saved. However, if you Check Out a document to the web tray, edit it, and then Check the document back in, Edit function from the context menu is no longer available for that document.
This is by product design.

If you want to edit the documents directly with Right Click --> Edit or in the Viewer --> Tools --> Edit and the new versions have to be created automatically, then please activate the option „Automatically create new versions“ for the file cabinet in the Web Configuration:

After that you don't need to Check Out and In the documents in order to create a new version, but every time you edit the document the version's number will be generated.
Unfortunately it can not be changed for the documents that are already checked out with the manual version management, but for all other documents the edit will be possible also with version management.